What Is A Follow Focus?

Autofocus is rarely used in professional film making because the focus mechanisms are not smooth enough to be adjusted while the camera is rolling.  Instead, the focus ring on the lens is rotated manually using a geared hand controller called a follow focus.  Sometimes the follow focus is turned by the camera operator and sometimes there is a dedicated member of the camera crew called a focus puller.

All cine lenses are manual focus only, designed to be operated smoothly with a follow focus and they have teeth around the focus ring that mesh with the gearing on controller.  DSLR lenses can also be used with a follow focus by attaching after-market gears to the lens.  The process is quick, simple and cheap, and the lightweight nature of DSLR lenses has made the a popular option in recent years.  Not to mention the fact that DSLR lenses can be 10X cheaper than a cine lens.

A good follow focus needs to have a very precise manufacturing tolerance in the gears and bearings, so they can be quite expensive, ranging from $500 right up into the several thousands!

 

Additional Reading

what is a follow focus

 

A follow focus

 

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Canon Cine lenses showing the gearing around the lens which meshes with the follow focus to ensure smooth manual focus.